Invasion Ecology Flashcards
What is the invasion process?
- transport leads to either introduction or death and captivity
- introduction leads to either fail or establish
- establish leads to either remain locol or spread
- spread leads to either low or high impact depending on human perception
How invasive species spread:
- trade routes between Europe, West Africa and Caribbean
- shipping lanes and coal ports
- ports were first to experience invasive species
- spread to smaller ports
What are bio-control agents?
- Controls pests using other living organisms
- relies on predation, parasitism, herbivory and other natural mechanisms
- involves an active management role
- involves either importation, augmentation or conservation to control pests
Causes of adverse impact on native species:
- habitat alteration
- introduction of invasive species
Where are the majority of invasive species?
- in temperate regions
What is the model used for invasibility?
E = I X S
- E = number of exotics present
- I = number of species introductions
- S = survival rate of introductions
Components of I and S
- I = Ia + Ii
where Ia is intentional release and Ii is accidental releases
- S = SvShScSm
where Sv = competition, Sh = herbivory and pathogens, Sc = chance events and Sm = maladaptation
Are islands more invasible than mainlands?
- higher number of invasive species on Vancouver Island may be due to number of species introductions not related to mechanisms in establishment stage (e.g. disturbance, competition)
- non-native and native species richness are positively correlated and it occurs REGARDLESS of whether the area is an island or mainland
What is a propagule?
- set of non native individuals released in new environment
What are the three elements of propagule pressure?
- number of individuals released per event
- number of release events
- health of released individuals
What are the four main introductions to New Zealand?
- Polynesian settlers bringing two mammals (pacific rat and maori dog)
- Captain Cook arrives with goats
- European sealing and whalers arrive and exhaust the stock - Norway rat, black rat and mice introduced through the ships
- Large influx of European settlers, introducing more terrestrial vertebrates
What are the classification for disturbances?
- natural vs. anthropogenic
- wild fire vs. prescribed burn
- biotic vs. abiotic
- prairie dog vs. deep plowed grasslands
- endogenous vs. exogenous
- succession vs. tree planting
What is a disturbance?
- event in time that disrupts ecosystem, community or population structure and changes resources, substrate availability or physical environment
What is the range of events and processes for disturbances?
- intensity
- frequency
- duration
- predictability
- distribution
- synergism
What is the probability of a community invasion?
- within a community resistance
- abiotic and biotic resistance
VS.
- propagule pressure
What happens after a community is invaded?
- resistance can decrease after invasion making community more susceptible
eg. Garry oak communities invaded by scotch broom and later daphne
What is the theory of fluctuating resource availability?
- Resource changes:
- Pulse A to B eg. eutrophication caused by run-off
- Decline A to C eg. overgrazing
- Both A to D eg. nutrient increase and overgrazing
- A to D is easily invasible
- communities susceptibility to invasion increases as resource availability increases
